Fix use of Closure in EquidimensionalQuasiAffineDecomposition.
Install \= and IsSubset more generically.

They now work for affine schemes returned by Spec.
Install QuasiAffineDecomposition for all quasi-affine subschemes.
Add example for EquidimensionalQuasiAffineDecomposition.
Merge pull request #3 from brain0/working

Working